Cooling system for the cooling of the housing of a rotary piston internal combustion engine

ABSTRACT

A cooling system with a liquid cooling medium for cooling the housing of a rotary piston internal combustion engine, especially of trochoidal construction, which consists of at least one casing, of end parts and possibly of one or several intermediate parts, in which the cooling system consists of at least two cooling circulations which are completely separated from one another; the cooling media of the two cooling circulations may thereby have different temperatures.

United States Patent 1 Lamm l l Nov. 25, 1975 I COOLING SYSTEM FOR THECOOLING OF THE HOUSING OF A ROTARY PISTON INTERNAL COMBUSTION ENGINE[75] Inventor: Heinz Lamm,Esslingen-St.

Bernhardt, Germany [73] Assignee: Daimler-Benz Aktiengesellschaft,

Stuttgart, Germany [22} Filed: Oct. 6, I972 [2i] App], No.: 295,481

[44] Published under the Trial Voluntary Protest Program on January 28,1975 as document no.

[30] Foreign Application Priority Data Oct, 9, [971 Germany 2150478 [52]US. Cl. l23/8.0l; 4l8/83 [5 1] Int. Cl. F02B 55/10 [58] Field of Search123/801, 4|.29; 418/83.

[56] References Cited UNITED STATES PATENTS 3,298,330 l/l967 Ryusuke Itoet al l23/8.0I

3,444,845 5/l969 Scheiterlein l23/4l.29 X

OTHER PUBLICATIONS Curtiss-Wright's Experimental Rotating CombustionEngines," by Dr Max Bentele, (Received l0l463).

Primary ExaminerC. J. Husar Assistant ExaminerMichael Koczo, Jr.Attorney, Agent, or FirmCraig & Antonelli ABSTRACT A cooling system witha liquid cooling medium for cooling the housing of a rotary pistoninternal combustion engine, especially of trochoidal construction, whichconsists of at least one casing, of end parts and possibly of one orseveral intermediate parts, in which the cooling system consists of atleast two cooling circulations which are completely separated from oneanother; the cooling media of the two cooling circulations may therebyhave different temperatures.

28 Claims, 2 Drawing Figures VEHICLE HEATER US Patent Nov. 25, 19753,921,593

VEHICLE HEATER FIGI COOLING SYSTEM FOR THE COOLING OF THE HOUSING OF AROTARY PISTON INTERNAL COMBUSTION ENGINE as well as of the intermediateand end parts changes only slightly and that the gas-tightness betweenthe individual housing parts is considerably improved. Thisgas-tightness cannot be assured in the prior art cooling The presentinvention relates to a cooling system 5 systems since none of thecustomary elastic seals can be with a liquid cooling medium for purposesof cooling a housing consisting at least of a casing, of end parts andpossibly of one or several intermediate parts of a rotary pistoninternal combustion engine, especially of trochoidal type ofconstruction.

Such types of prior art cooling systems consist of one coolingcirculation which especially in rotary piston internal combustionengines with several disks, represents a widely extended and branchedsystem. Since in a rotary piston internal combustion engine, incontrast, for example, to a reciprocating piston internal combustionengine, the heat yield, i.e., the amount of heat produced is verydifferent in the individual areas, the cooling system has to be matchedvery carefully. Thus, throttling places for the cooling medium areinstalled in order to supply the individual areas with differentquantities of cooling medium. This entails the disadvantage that thecooling medium pump has to be dimensioned very large and that itpossesses a very high input power. Notwithstanding a careful matching,however, local overheatings cannot be avoided by reason of anunfavorable distribution of the cooling medium or by reason ofinadequate venting.

The present invention is concerned with the task to avoid theaforementioned shortcomings. The underlying problems are solvedaccording to the present invention in that the cooling system consistsof at least two completely separate cooling circulatory systems.

By reason of the construction of the cooling system in accordance withthe present invention, the cooling medium quantities in each coolingmedium circulation are considerably smaller than if only one singlecooling circulation were present. Throttling places are not necessary inthe cooling system, and the matching of 'the cooling system isconsiderably facilitated. Also, the small cooling medium quantity ineach cooling circulatory system brings about a very rapid heat-up of thecooling medium after a cold start.

The cooling system is further improved according to an advantageousembodiment of the present invention in that the cooling media of thedifi'erent cooling circulatory systems have differently hightemperatures. The cooling media may thereby consist of differentsubstances depending on the temperature.

The cooling system is further improved according to the presentinvention in that the cooling media of the different cooling circulatorysystems cool different areas of the housing having differing heat yieldor heat production. These differing heat quantities can be conductedaway either by differing cooling medium quantities or with the aid ofdifferent cooling medium temperatures if a cooling circulatory systemwith lower cooling medium temperature is consequently coordinated to anarea of the housing with higher heat yield. In case the temperature ofthe hottest cooling medium is selected sufficiently high, heat can begiven off from the cooling medium to the housing in individual,particularly cool areas of the housing. As a result thereof, the housingassumes everywhere an approximately equal temperature which alsosignifies a uniform housing expansion. The advantages resultingtherefrom are that the form and shape of the running surface of thecasing arranged between the housing parts for thermal reasons and themetallic seal is only very inadequate by reason of non-uniformtemperature distribution and local overheating with the elastic andplastic deformation re- 10 sulting therefrom.

It is furthermore advantageous if the cooling medium of one coolingcirculatory system enters the housing at the place of the area to becooled where the largest heat quantity of this area is produced or inproximity 15 thereof, and leaves at the place with lowest heat yield orin proximity thereof. The temperature of the housing can thus be keptapproximately the same also at the individual places of an area sincethe entering relatively cool cooling water absorbs a larger amount ofheat then the already heated discharged cooling water.

In a cooling system for cooling the housing of a rotary piston internalcombustion engine of trochoidal type of construction with a two-archedtrochoidal running surface arranged in the casing, along which slides atriangular piston with its corners, and with one inlet and one outletchannel each arranged in the casing, the cooling system of thisinvention may consist of two cooling circulations with differingtemperatures, of which the cooler cooling circulation flows through thearea of the casing opposite the inlet and outlet channel whereas thehotter cooling medium flows through the adjacent area of the casingadjoining in the direction of the piston up to the area of the inletchannel or therebeyond up to the area in which the combustion gases arepresent during the beginning of the suction cycle. The cooler coolingmedium thus cools the area with the greatest heat yield, therefore thatarea in which the combustion gases give off heat to the casing at theend of the compression and during the combustion whereas 0 the hottercooling medium cools the area of the casing inclusive the outlet channelin which the combustion gases give off heat during the expansion andexhaust cycle.

In case in this cooling system of the present invention the coolingmedia of the two cooling circulations enter into the casing at adjacentplaces of the two areas, then they cool at first the hottest places ofthe rotary piston internal combustion engine; namely, the vicinitythereof in which the combustion gases are present at the beginning ofthe expansion cycle, and then flow toward the coolest places for therespective areas thereof.

The cooling medium may additionally flow through the housing end partsand possibly the housing intermediate parts in those areas whichdirectly adjoin the area disposed within the casing and traversed by thesame, whereas the hotter cooling medium flows through the areas of theend parts and possibly of the intermediate parts adjoining these areasin the direction toward the center longitudinal axis of the rotarypiston internal combustion engine. The areas traversed by the coolercooling medium are thus disposed, as viewed in the direction of thelongitudinal axis of the rotary piston internal combustion engine, allone behind the other so that the inlet and outlet of the cooling mediumis particularly simple. With this cooling system, the areas of the endand lateral housing parts which are thermally loaded particularlyhighly, are cooled by both cooling media whereas the other areas arecooled by means of oil in a conventional manner.

If at least the hottest cooling medium is heated by the exhaust gases ofthe rotary piston internal combustion engine, any eventual heat lossescan be compensated for which occur when heat is given off toparticularly cool parts of the housing. Additionally, the cold startingtime is considerably shortened thereby.

In a cooling system for cooling the housing of a rotary piston internalcombustion engine which is installed into a motor vehicle with a vehicleheating system, the heating medium of the vehicle heater can be heatedup in an advantageous manner by the hottest cooling medium whereby theheating effect commences particularly rapidly and intensively.

Accordingly, it is an object of the present invention to provide acooling system for cooling the housing of a rotary piston internalcombustion engine which avoids by simple means the aforementionedshortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a cooling system forcooling the housing of a rotary piston internal combustion engine inwhich not only the cooling medium pump does not have to be selected verylarge, but also the difficulties in matching the cooling system to thelocal, individual requirements is farreachingly dispensed with.

A further object of the present invention resides in a cooling systemfor cooling the housing of a rotary piston internal combustion engine,particularly of trochoidal construction, which effectively avoids localoverheating by the use of at least two completely separate coolingcirculations.

Still a further object of the present invention resides in a coolingsystem for cooling the housing of a rotary piston internal combustionengine which obviates the need for throttling places as well ascomplicated designs of the passages for the cooling medium.

Still another object of the present invention resides in a coolingsystem for rotary piston internal combustion engines which also improvesthe heat-up of the cooling medium after a cold start.

A further object of the present invention resides in a cooling systemfor rotary piston internal combustion engines in which the differentcooling circulations cool different areas of the housing with differingheat yield so as to optimize the cooling effect and match it to thelocal requirements.

A further object of the present invention resides in a cooling systemfor a rotary piston internal combustion engine which assures uniformthermal expansion of the housing as well as improved gas-tightnessbetween individual housing parts.

Another object of the present invention resides in a cooling system forrotary piston internal combustion engines which also improves theheating effect of the heater of the motor vehicle.

These and other objects, features and advantages of the presentinvention will become more apparent from the following description whentaken in connection with the accompanying drawing, which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein:

FIG. 1 is a cross-sectional view through the casing of a rotary pistoninternal combustion engine in accordance with the present inventiontaken at right angle to the engine axis; and

FIG. 2 is a similar cross-sectional view through an end portion of thesame rotary piston internal combustion engine in accordance with thepresent invention.

Referring now to the drawing wherein like reference numerals are usedthroughout the two views to designate like parts, the casing l of FIG. 1is delimited toward the inside thereof by a two-arched trochoidalrunning surface 2, along which slides the rotating piston 4 with itspiston corners 5 in the direction of arrow 3. An inlet channel 6 and anexhaust channel 7 are arranged in the casing 1 along one longitudinalside. An aperture 8 for a spark plug (not shown) is provided in thecasing 1 along the oppositely disposed longitudinal side while anaperture 9 for an injection nozzle (not shown) is provided between theaperture 8 for the spark plug and the inlet channel 6. Through-passageopenings 10 for tie rods are provided distributed over the circumferencewhich hold together the individual housing parts.

The casing l is cooled by cooling media of different temperaturesflowing in two cooling circulatory systems completely separate from oneanother. The cooler cooling medium which, for example, has a temperatureof C., flows through a cooling chamber 11 disposed in the casing 1 whichextends along the entire longitudinal side on which is disposed thespark plug, up to the trochoidal running surface 2. The opening 8 forthe spark plug is surrounded by the cooling chamber 11. The inletchannel 12 into the cooling chamber 11 is located at the end thereof, asviewed in the direction of rotation 3 of the piston 4, whereas theoutlet channel 13 is disposed at the other end so that the coolingmedium flows through the cooling chamber 11 opposite the direction ofrotation 3 of the piston 4.

A cooling chamber 14 of the second cooling circulatory system, whosecooling medium has a temperature of, for example, C., adjoins thecooling chamber 11 in the direction of rotation 3 of the piston 4 andextends up to the inlet channel 6 whereby it surrounds the exhaustchannel 7. The inlet channel 15 into the cooling chamber 14 is disposedin proximity to the inlet channel 12 of the other cooling chamber 11whereas the outlet channel 16 is disposed in proximity of the inletchannel 6. The continuation of this outlet channel 16 is represented bythe channel 28 in the end part 17 (FIG. 2) and possibly in theintermediate parts. The cooling medium of the two cooling circulationsthus enter into the cooling chambers 11 and 14 within an area in whichthe combustion gases have the highest temperature and in which thelargest heat quantity is thus produced, and flow in the cooling chambers11 and 14 toward those places in which the smallest heat quantity forthe corresponding areas to be cooled is produced.

In the end part 17 illustrated in FIG. 2 are also provided two coolingchambers 18 and 19 which belong to the same cooling circulations as thecooling chambers 11 and 14, respectively. The cooling chamber 18traversed by the cooler cooling medium is disposed directly adjacent thecooling chamber 1 l of the casing I so that all cooling chambers l1, l8belonging to this cooling circulation are arranged approximately alignedone behind the other as viewed in the direction of the centerlongitudinal axis 20 (FIG. 2) of the rotary piston internal combustionengine. The same is also true for the inlet channels 21 and outletchannels 22 in relation to the inlet channels 12 and the outlet channels13 in the casing l. A very simple guidance and conduction of the coolingmedium stream results therefrom.

The cooling chamber 19 adjoins the cooling chamber 18 in the directiontoward the center of the rotary piston internal combustion engine. Ribs27 arranged therein are to assure a good cooling medium guidance andconduction. The inlet channel 23 is disposed accurately in front or tothe rear of the inlet channel 15 within the casing 1 whereas the outletchannel 24 is disposed in proximity of the outlet channel 22. Thecontinuation of the outlet channel 24 is represented by the channel 25in the casing 1 (FIG. 1). The areas of the end part 17 not cooled by thecooling media of the two cooling circulations are cooled by lubricatingoil which emerges out of the bearing of the piston 4 and leaves thehousing by way of the aperture 26.

As can be seen from the foregoing, the cooler medium not only flowsthrough the chamber 11 in the casing 1 but additionally flows throughthe end parts 17 and possibly through intermediate parts of a multi-diskconstruction by way of chambers 18 located in those areas which directlyadjoin the area traversed by the cooler cooling medium in the casing 1by way of chamber 11; the hotter cooling medium, in turn, not only flowsthrough the chamber 14 in the casing l, but also through the end parts17 and possibly intermediate parts of a multi-disk construction by wayof chambers 19 located in those areas directly adjoining the areas ofthe chambers 18 in the direction toward the center longitudinal axis 20of the rotary piston internal combustion engine.

In case the motor vehicle into which the rotary piston internalcombustion engine is installed is equipped with a vehicle heater, thenthe hottest cooling medium which may be heated by the exhaust gases ofthe rotary piston internal combustion engine can be used to heat theheating medium of the vehicle heater. (See schematic showing of thevehicle heater in FIG. 1).

While I have shown and described only one embodiment in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to those skilled in the art, and I therefore do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifcations as are encompassed by the scope of theappended claims.

What is claimed is:

l. A cooling system for cooling housing means of a rotary pistoninternal combustion engine of the type having housing means enclosing acombustion space within which a multi-lobed rotary piston rotates, thehousing means including a casing means circumferentially surrounding thepiston. the casing means having an inwardly facing running surfaceengageable with outer portions of the lobes of the piston duringrotation thereof, the engine including inlet and outlet channels forrespectively accommodating entry of combustible materials into thecombustion space and exit of exhaust gases from the combustion space,the running surface and piston being so configured and the inlet andoutlet channels being so positioned that combustion gases of differingtemperatures are in contact with different circumferential portions ofthe running surface during operation of the engine; said cooling systemcomprising:

a first cooling circuit for accommodating circulation of a first coolingfluid.

and a second cooling circuit for accommodating circulation of a secondcooling fluid,

said first and second circuits being separate from one another,

said first cooling circuit including a first cooling space formed insaid casing means and extending adjacent a first portion of thecircumference of said running surface with a cooling fluid inlet to saidfirst cooling space positioned adjacent the circumferential portion ofthe running surface which is in contact with the hottest combustiongases during operation of the engine,

wherein said first cooling space extends around the circumference ofsaid running surface in a direction opposite the rotational direction ofthe piston from said cooling fluid inlet to a cooling fluid outletpositioned adjacent the circumferential portion of the running surfacewhich is in contact with the coolest combustion gases during operationof the engine.

2. A cooling system according to claim 1, wherein said second coolingcircuit includes a second cooling space formed in said casing means andextending adjacent a second portion of the circumference of said runningsurface which is circumferentially spaced from said first portion of therunning surface.

3. A cooling system according to claim 2, wherein said second coolingspace extends in the direction of rotation of the piston from a coolingfluid inlet thereof located adjacent the cooling fluid inlet of saidfirst cooling space to a cooling fluid outlet thereof.

4. A cooling system according to claim 3, wherein said running surfaceincludes openings for said inlet and outlet channels and for saidignition means, wherein the openings for said inlet and outlet channelsare disposed at the opposite side of said combustion space with respectto said opening for the ignition means, and wherein said inlets for saidfirst and second cooling spaces are positioned intermediate the openingfor the ignition means and the opening for the outlet channel as seen inthe direction of rotation of the piston.

5. A cooling system according to claim 4, wherein the opening for theoutlet channel, the opening for the inlet channel, and the opening forthe ignition means are serially arranged with respect to one another asseen in the direction of rotation of the piston.

6. A cooling system ac cording to claim 5, wherein the outlet for thefirst cooling space is disposed between said opening for the ignitionmeans and said opening for the inlet channel.

7. A cooling system according to claim 6, wherein the outlet for thesecond cooling space is disposed at the side of the opening for theoutlet channel closest to the opening for the ignition means as seen inthe direction of rotation of the piston.

8. A cooling system according to claim 7, wherein said second coolingcircuit includes further cooling spaces formed in said casing meansbetween said openings for the inlet and outlet channels and adjacent theoutlet for said first cooling space.

9. A cooling system according to claim 4, wherein said second coolingcircuit includes further cooling spaces formed in said casing meansbetween said openings for the inlet and outlet channels and adjacent theoutlet for said first cooling space.

10. A cooling system according to claim 5, wherein said running surfaceis of two-arched trochoidal construction, wherein said piston is a threelobed piston, and wherein the first cooling fluid is maintained coolerthan the second cooling fluid.

11. A cooling system according to claim 1, wherein said running surfaceis of two-arched trochoidal con struction, wherein said piston is athree lobed piston, and wherein the first cooling fluid is maintainedcooler than the second cooling fluid.

12. A cooling system according to claim 9, wherein said running surfaceis of two-arched trochoidal construction, wherein said piston is a threelobed piston, and wherein the first cooling fluid is maintained coolerthan the second cooling fluid.

13. A cooling system according to claim 12, wherein the cooling spacesof said second circuit which is located adjacent the outlet of the firstcooling space is located adjacent an area of the combustion space wherethe combustion gases are experiencing the beginning of the suctioncycle.

14. A cooling system, for cooling housing means of a rotary pistoninternal combustion engine of the type having housing means enclosing acombustion space within which a multi-lobed rotary piston rotates, thehousing means including a casing means circumferentially surrounding thepiston, the casing means having an inwardly facing running surfaceengageable with outer portions of the lobes of the piston duringrotation thereof, the engine including inlet and outlet channels forrespectively accommodating entry of combustible materials into thecombustion space and exit of exhaust gases from the combustion space,the running surface and piston being so configured and the inlet andoutlet channels being so positioned that combustion gases of differingtemperatures are in contact with different circumferential portions ofthe running surface during operation of the engine; said cooling systemcomprising:

a first cooling circuit for accommodating circulation of a first coolingfluid,

and a second cooling circuit for accommodating circulation of a secondcooling fluid,

said first and second circuits being separate from one another,

said first cooling circuit including a first cooling space formed insaid casing means and extending adjacent a first portion of thecircumference of said running surface with a cooling fluid inlet saidfirst cooling space positioned adjacent the circumferential portion ofthe running surface which is in contact with the hottest combustiongases during operation of the engine,

wherein said housing means includes an end part adjacent said casingmeans for laterally closing an axial end of said combustion space,wherein said first cooling circuit includes a cooling space formed insaid end part, wherein said second cooling circuit includes a coolingspace formed in said end part, and wherein the cooling space in said endpart of said first cooling circuit is axially aligned and immediatelyadjacent the first cooling space.

15. A cooling system according to claim 14, wherein the cooling space insaid end part of said second cooling circuit extends circumferentiallyadjacent to and radially inwardly of said cooling space in said end partof said first cooling circuit such that both of said cooling spaces insaid end part are disposed at the same side of the rotational axis ofthe piston.

16. A cooling system according to claim 15, wherein the flow of coolingfluid in both of said cooling spaces in said end part is in the samecircumferential direction with respect to the direction of rotation ofthe piston.

17. A cooling system according to claim 16, wherein the circumferentialextent of the cooling space in said end part of said second coolingcircuit is greater than the circumferential extent of the cooling spacein said end part of said first cooling circuit with the respectiveinlets and outlets of the cooling space of said second cooling circuitspaced circumferentially outside of the respective inlets and outlets ofthe cooling space of said first cooling circuit.

18. A cooling system according to claim 17, wherein said end partincludes lubricant accommodating space over portions thereof unoccupiedby the cooling spaces of said first and second cooling circuits foraccommodating flow of lubricant through said end part, which lubricantcommunicates with lubricating means for the piston.

19. A cooling system according to claim 15, wherein said running surfaceis of two-arched trochoidal construction, wherein said piston is a threelobed piston, and wherein the first cooling fluid is maintained coolerthan the second cooling fluid.

20. A cooling system according to claim 10, further comprising a vehicleheater means, wherein said second cooling circuit includes means foraccommodating heat exchange between the second fluid medium and saidvehicle heater means, and wherein said second cooling medium ismaintained at a higher temperature than is said first cooling medium.

21. A cooling system according to claim 1, wherein said first fluidmedium is maintained cooler than said second fluid medium.

22. A cooling system for cooling housing means of a rotary pistoninternal combustion engine of the type having housing means enclosing acombustion space within which a multi-lobed rotary piston rotates, thehousing means including a casing means circumferentially surrounding thepiston and an end part adjacent said casing means for laterally closingan axial end of said combustion space, the casing means having aninwardly facing running surface engageable with outer portions of thelobes of the piston during rotation thereof, the engine including inletand outlet channels for respectively accommodating entry of combustiblematerials into the combustion space and exit of exhaust gases from thecombustion space, the running surface and piston being so configured andthe inlet and outlet channels being so positioned that combustion gasesof differing temperatures are in contact with different circumferentialportions of the running surface during operation of the engine; saidcooling system comprising:

a first cooling circuit for accommodating circulation of a first coolingfluid,

and a second cooling circuit for accommodating circulation of a secondcooling fluid,

said first and second circuits being separate from one another,

said first and second cooling circuits including respective separatecooling spaces formed in said end part, the cooling space in said endpart of said second cooling circuit extending circumferentially adjacentto and radially inwardly of said cooling space in said end part of saidfirst cooling circuit such that both of said cooling spaces in said endpart are disposed at the same side of the rotational axis of the piston.

23. A cooling system according to claim 22, wherein said first coolingcircuit includes a first cooling space formed in said casing means andextending adjacent a first portion of the circumference of said runningsurface, and wherein the cooling space in said end part of said firstcooling circuit is axially aligned and immediately adjacent the firstcooling space.

24. A cooling system according to claim 22, wherein the flow of coolingfluid in both of said cooling spaces in said end part is in the samecircumferential direction with respect to the direction of rotation ofthe piston.

25. A cooling system according to claim 24, wherein the circumferentialextent of the cooling space in said end part of said second coolingcircuit is greater than the circumferential extent of the cooling spacein said end part of said first cooling circuit with the respectiveinlets and outlets of the cooling space of said second cooling circuitspaced circumferentially outside of the respective inlets and outlets ofthe cooling space of said first cooling circuit.

26. A cooling system according to claim 22, wherein said running surfaceis of twoarched trochoidal construction, wherein said piston is a threelobed piston, and wherein the first cooling fluid is maintained coolerthan the second cooling fluid.

27. A cooling system according to claim 25, wherein said end partincludes lubricant accommodating space over portions thereof unoccupiedby the cooling spaces of said first and second cooling circuits foraccommodating flow of lubricant through said end part, which lubricantcommunicates with lubricating means for the piston.

28. A cooling system according to claim 27, wherein said running surfaceis of two-arched trochoidal construction, wherein said piston is a threelobed piston, and wherein the first cooling fluid is maintained coolerthan the second cooling fluid.

II I l l

1. A cooling system for cooling housing means of a rotary pistoninternal combustion engine of the type having housing means enclosing acombustion space within which a multi-lobed rotary piston rotates, thehousing means including a casing means circumferentially surrounding thepiston, the casing means having an inwardly facing running surfaceengageable with outer portions of the lobes of the piston duringrotation thereof, the engine including inlet and outlet channels forrespectively accommodating entry of combustible materials into thecombustion space and exit of exhaust gases from the combustion space,the running surface and piston being so configured and the inlet andoutlet channels being so positioned that combustion gases of differingtemperatures are in contact with different circumferential portions ofthe running surface during operation of the engine; said cooling systemcomprising: a first cooling circuit for accommodating circulation of afirst cooling fluid, and a second cooling circuit for accommodatingcirculation of a second cooling fluid, said first and second circuitsbeing separate from one another, said first cooling circuit including afirst cooling space formed in said casing means and extending adjacent afirst portion of the circumference of said running surface with acooling fluid inlet to said first cooling space positioned adjacent thecircumferential portion of the running surface which is in contact withthe hottest combustion gases during operation of the engine, whereinsaid first cooling space extends around the circumference of saidrunning surface in a direction opposite the rotational direction of thepiston from said cooling fluid inlet to a cooling fluid outletpositioned adjacent the circumferential portion of the running surfacewhich is in contact with the coolest combustion gases during operationof the engine.
 2. A cooling system according to claim 1, wherein saidsecond cooling circuit includes a second cooling space formed in saidcasing means and extending adjacent a second portion of thecircumference of said running surface which is circumferentially spacedfrom said first portion of the running surface.
 3. A cooling systemaccording to claim 2, wherein said second cooling space extends in thedirection of rotation of the piston from a cooling fluid inlet thereoflocated adjacent the cooling fluid inlet of said first cooling space toa cooling fluid outlet thereof.
 4. A cooling system according to claim3, wherein said running surface includes openings for said inlet andoutlet channels and for said ignition means, wherein the openings forsaid inlet and outlet channels are disposed at the opposite side of saidcombustion space with respect to said opening for the ignition means,and wherein said inlets for said first and second cooling spaces arepositioned intermediate the opening for the ignition means and theopening for the outlet channel as seen in the direction of rotation ofthe piston.
 5. A cooling system according to claim 4, wherein theopening for the outlet channel, the opening for the inlet channel, andthe opening for the ignition means are serially arranged with respect toone another as seen in the direction of rotation of the piston.
 6. Acooling system according to claim 5, wherein the outlet for the firstcooling space is disposed between said opening for the ignition meansand said opening for the inlet channel.
 7. A cooling system according toclaim 6, wherein the outlet for the second cooling space is disposed atthe side of the opening for the outlet channel closest to the openingfor the ignition means as seen in the direction of rotation of thepiston.
 8. A cooling system according to claim 7, wherein said secondcooling circuit includes further cooling spaces formed in said casingmeans between said openings for the inlet and outlet channels andadjacent the outlet for said first cooling space.
 9. A cooling systemaccording to claim 4, wherein said second cooling circuit includesfurther cooling spaces formed in said casing means between said openingsfor the inlet and outlet channels and adjacent the outlet for said firstcooling space.
 10. A cooling system according to claim 5, wherein saidrunning surface is of two-arched trochoidal construction, wherein saidpiston is a three lobed piston, and wherein the first cooling fluid ismaintained cooler than the second cooling fluid.
 11. A cooling systemaccording to claim 1, wherein said running surface is of two-archedtrochoidal construction, wherein said piston is a three lobed piston,and wherein the first cooling fluid is maintained cooler than the secondcooling fluid.
 12. A cooling system according to claim 9, wherein saidrunning surface is of two-arched trochoidal construction, wherein saidpiston is a three lobed piston, and wherein the first cooling fluid ismaintained cooler than the second cooling fluid.
 13. A cooling systemaccording to claim 12, wherein the cooling spaces of said second circuitwhich is located adjacent the outlet of the first cooling space islocated adjacent an area of the combustion space where the combustiongases are experiencing the beginning of the suction cycle.
 14. A coolingsystem, for cooling housing means of a rotary piston internal combustionengine of the type having housing means enclosing a combustion spacewithin which a multi-lobed rotary piston rotates, the housing meansincluding a casing means circumferentially surrounding the piston, thecasing means having an inwardly facing running surface engageable withouter portions of the lobes of the piston during rotation thereof, theengine including inlet and outlet channels for respectivelyaccommodating entry of combustible materials into the combustion spaceand exit of exhaust gases from the combustion space, the running surfaceand piston being so configured and the inlet and outlet channels beingso positioned that combustion gases of differing temperatures are incontact with different circumferential portions of the running surfaceduring operation of the engine; said cooling system comprising: a firstcooling circuit for accommodating circulation of a first cooling fluid,and a second cooling circuit for accommodating circulation of a secondcooling fluid, said first and second circuits being separate from oneanother, said first cooling circuit including a first cooling spaceformed in said casing means and extending adjacent a first portion ofthe circumference of said running surface with a cooling fluid inleTsaid first cooling space positioned adjacent the circumferential portionof the running surface which is in contact with the hottest combustiongases during operation of the engine, wherein said housing meansincludes an end part adjacent said casing means for laterally closing anaxial end of said combustion space, wherein said first cooling circuitincludes a cooling space formed in said end part, wherein said secondcooling circuit includes a cooling space formed in said end part, andwherein the cooling space in said end part of said first cooling circuitis axially aligned and immediately adjacent the first cooling space. 15.A cooling system according to claim 14, wherein the cooling space insaid end part of said second cooling circuit extends circumferentiallyadjacent to and radially inwardly of said cooling space in said end partof said first cooling circuit such that both of said cooling spaces insaid end part are disposed at the same side of the rotational axis ofthe piston.
 16. A cooling system according to claim 15, wherein the flowof cooling fluid in both of said cooling spaces in said end part is inthe same circumferential direction with respect to the direction ofrotation of the piston.
 17. A cooling system according to claim 16,wherein the circumferential extent of the cooling space in said end partof said second cooling circuit is greater than the circumferentialextent of the cooling space in said end part of said first coolingcircuit with the respective inlets and outlets of the cooling space ofsaid second cooling circuit spaced circumferentially outside of therespective inlets and outlets of the cooling space of said first coolingcircuit.
 18. A cooling system according to claim 17, wherein said endpart includes lubricant accommodating space over portions thereofunoccupied by the cooling spaces of said first and second coolingcircuits for accommodating flow of lubricant through said end part,which lubricant communicates with lubricating means for the piston. 19.A cooling system according to claim 15, wherein said running surface isof two-arched trochoidal construction, wherein said piston is a threelobed piston, and wherein the first cooling fluid is maintained coolerthan the second cooling fluid.
 20. A cooling system according to claim10, further comprising a vehicle heater means, wherein said secondcooling circuit includes means for accommodating heat exchange betweenthe second fluid medium and said vehicle heater means, and wherein saidsecond cooling medium is maintained at a higher temperature than is saidfirst cooling medium.
 21. A cooling system according to claim 1, whereinsaid first fluid medium is maintained cooler than said second fluidmedium.
 22. A cooling system for cooling housing means of a rotarypiston internal combustion engine of the type having housing meansenclosing a combustion space within which a multi-lobed rotary pistonrotates, the housing means including a casing means circumferentiallysurrounding the piston and an end part adjacent said casing means forlaterally closing an axial end of said combustion space, the casingmeans having an inwardly facing running surface engageable with outerportions of the lobes of the piston during rotation thereof, the engineincluding inlet and outlet channels for respectively accommodating entryof combustible materials into the combustion space and exit of exhaustgases from the combustion space, the running surface and piston being soconfigured and the inlet and outlet channels being so positioned thatcombustion gases of differing temperatures are in contact with differentcircumferential portions of the running surface during operation of theengine; said cooling system comprising: a first cooling circuit foraccommodating circulation of a first cooling fluid, and a second coolingcircuit for accommodating circulation of a second cooling fluid, saidfirst and second circuits being separate from one another, Said firstand second cooling circuits including respective separate cooling spacesformed in said end part, the cooling space in said end part of saidsecond cooling circuit extending circumferentially adjacent to andradially inwardly of said cooling space in said end part of said firstcooling circuit such that both of said cooling spaces in said end partare disposed at the same side of the rotational axis of the piston. 23.A cooling system according to claim 22, wherein said first coolingcircuit includes a first cooling space formed in said casing means andextending adjacent a first portion of the circumference of said runningsurface, and wherein the cooling space in said end part of said firstcooling circuit is axially aligned and immediately adjacent the firstcooling space.
 24. A cooling system according to claim 22, wherein theflow of cooling fluid in both of said cooling spaces in said end part isin the same circumferential direction with respect to the direction ofrotation of the piston.
 25. A cooling system according to claim 24,wherein the circumferential extent of the cooling space in said end partof said second cooling circuit is greater than the circumferentialextent of the cooling space in said end part of said first coolingcircuit with the respective inlets and outlets of the cooling space ofsaid second cooling circuit spaced circumferentially outside of therespective inlets and outlets of the cooling space of said first coolingcircuit.
 26. A cooling system according to claim 22, wherein saidrunning surface is of two-arched trochoidal construction, wherein saidpiston is a three lobed piston, and wherein the first cooling fluid ismaintained cooler than the second cooling fluid.
 27. A cooling systemaccording to claim 25, wherein said end part includes lubricantaccommodating space over portions thereof unoccupied by the coolingspaces of said first and second cooling circuits for accommodating flowof lubricant through said end part, which lubricant communicates withlubricating means for the piston.
 28. A cooling system according toclaim 27, wherein said running surface is of two-arched trochoidalconstruction, wherein said piston is a three lobed piston, and whereinthe first cooling fluid is maintained cooler than the second coolingfluid.